U.S. patent number 8,758,551 [Application Number 13/922,892] was granted by the patent office on 2014-06-24 for substrate processing apparatus and electrode structure.
This patent grant is currently assigned to Tokyo Electron Limited. The grantee listed for this patent is Tokyo Electron Limited. Invention is credited to Tatsuya Handa.
United States Patent |
8,758,551 |
Handa |
June 24, 2014 |
Substrate processing apparatus and electrode structure
Abstract
A substrate processing apparatus capable of preventing the
abnormal discharge from being generated on a substrate. A housing
chamber houses the substrate. A mounting stage arranged in the
housing chamber, is configured to enable the substrate to be
mounted thereon. A disc-like electrode structure is connected to a
high-frequency power supply, and connected to a gas supply
apparatus via at least one gas supply system. The electrode
structure has therein at least one buffer chamber and a plurality
of connecting sections connected to the gas supply system. The
buffer chamber is communicated with the inside of the housing
chamber via a number of gas holes, and is communicated with the gas
supply system via the plurality of connecting sections. The
plurality of connecting sections for the buffer chamber are
arranged on the circumference of a circle centering around the
center of the electrode structure at equal intervals.
Inventors: |
Handa; Tatsuya (Nirasaki,
JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Tokyo Electron Limited |
Minato-ku |
N/A |
JP |
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Assignee: |
Tokyo Electron Limited
(Minato-ku, JP)
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Family
ID: |
39761472 |
Appl.
No.: |
13/922,892 |
Filed: |
June 20, 2013 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20130276982 A1 |
Oct 24, 2013 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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13617665 |
Sep 14, 2012 |
8480849 |
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12029728 |
Feb 12, 2008 |
8282770 |
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60938729 |
May 18, 2007 |
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Foreign Application Priority Data
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Mar 12, 2007 [JP] |
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2007-061749 |
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Current U.S.
Class: |
156/345.44;
156/345.34 |
Current CPC
Class: |
H01L
21/3065 (20130101); H01J 37/3244 (20130101); H01L
21/67069 (20130101); H01J 37/32091 (20130101); H01J
37/32541 (20130101) |
Current International
Class: |
H01L
21/306 (20060101); C23F 1/00 (20060101) |
Field of
Search: |
;156/345.44,345.34 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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08-325759 |
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Dec 1996 |
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JP |
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2001-127046 |
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May 2001 |
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JP |
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2003-257937 |
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Sep 2003 |
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JP |
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2006-66855 |
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Mar 2006 |
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JP |
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2007-335755 |
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Dec 2007 |
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JP |
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Primary Examiner: Chen; Keath
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier
& Neustadt, L.L.P.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is a continuation of U.S. application Ser.
No. 13/617,665 filed Sep. 14, 2012. U.S. application Ser. No.
13/617,665 is a continuation of U.S. application Ser. No.
12/029,728, filed on Feb. 12, 2008, the entire content of each are
incorporated herein by reference. U.S. application Ser. No.
12/029,728 claims the benefit of priority under 119(e) of U.S.
Provisional Application Ser. No. 60/938,729, filed May 18, 2007,
and claims the benefit of priority under 35 U.S.C. 119 from
Japanese Application No. 2007-061749 filed Mar. 12, 2007.
Claims
What is claimed is:
1. A substrate processing apparatus comprising: a chamber that
houses a disk-shaped substrate; a first electrode that is arranged
in the chamber, the substrate being mounted on the first electrode;
a second electrode constituting a shower head that is arranged such
as to face the mounted substrate and has a number of penetrating
gas holes, the second electrode has therein a space; a
high-frequency power source that supplies high-frequency power
between the first and second electrodes; a central vacancy that is
comprised of a central portion of the space in the shower head; at
least two annular buffer vacancies that are comprised of annular
spaces formed outside the central vacancy and arranged sequentially
in a radial direction of the shower head; a plurality of annular
partition wall members that divide the space in the shower head
with respect to the radial direction of the shower head such as to
form the central vacancy and the at least two annular buffer
vacancies; a plurality of pipes that are connected respectively to
the central vacancy and the at least two annular buffer vacancies
such as to supply processing gas and additional gas respectively to
the central vacancy and the at least two annular buffer vacancies;
and a branch flow rate adjusting apparatus that adjusts a flow rate
of the processing gas which flow through each of the plurality of
pipes; wherein each of the plurality of pipes is branched into at
least two branched pipes, and the branched pipes are connected to
each of the central vacancy and the at least two annular buffer
vacancies via at least two connecting sections which are disposed
on each of the central vacancy and the at least two annular buffer
vacancies along a circumference of a circle arranged thereon at
equal intervals, the at least two connecting sections belonging to
each of the central vacancy and the at least two annular buffer
vacancies are disposed symmetrically around the shower head center,
regarding all the connecting sections of the plurality of pipes,
one connecting section is shifted from another connecting section
adjacent thereto at constant degrees in a rotational system
centering around the center of the shower head, whereby a mixture
of the processing gas and the additional gas is supplied
symmetrically with respect to the center of the shower head and
uniformly into the chamber so as to make uniform the distribution
of an electric field generated in a processing space inside the
chamber.
2. A substrate processing apparatus as claimed in claim 1, wherein
the shower head is configured by a ceiling electrode plate, a
cooling plate, and an upper electrode body which are stacked in
this order from the side of the processing space of the chamber,
and the ceiling electrode plate, the cooling plate, and the upper
electrode body are made of a conductive material.
3. A substrate processing apparatus as claimed in claim 2, wherein
the cooling plate has a coolant chamber therein and at least two
coolant introducing sections from which a coolant is supplied to
the coolant chamber, and the coolant introducing sections are
arranged symmetrically with respect to the center of the shower
head.
4. A substrate processing apparatus as claimed in claim 1, wherein
the high-frequency power source is connected to the first
electrode.
5. A substrate processing apparatus as claimed in claim 1, wherein
the outside of a power supply tube which is directly connected to a
central portion of the shower head is covered by a case-shaped
grounding conductive member, and portions of the plurality of pipes
existing in the inside of the grounding conductive member are made
of an insulating material.
6. A substrate processing apparatus as claimed in claim 5, wherein
the portions of the plurality of pipes existing in the inside of
the grounding conductive member are made of a resin.
7. A substrate processing apparatus as claimed in claim 1, when the
total number of all the connecting sections is set to n, each of
all the connecting sections is arranged at each rotational angle of
360.degree./n.+-.3.degree. in the rotational system centering
around the center of the shower head.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a substrate processing apparatus
and an electrode structure, and more particularly to a substrate
processing apparatus including an electrode structure which is
connected to a high-frequency power supply and to a gas supply
apparatus adapted to supply processing gas.
2. Description of the Related Art
As a substrate processing apparatus 60 adapted to perform plasma
processing, for example, etching processing to a wafer W as a
substrate, there is known, as shown in FIG. 6, an apparatus
configured by including: a chamber 61 which houses the wafer W; a
mounting stage 62 which is arranged in the chamber 61 and on which
the wafer W is mounted; and a disc-like shower head 63 which is
arranged opposite to the mounting stage 62, and which introduces
processing gas into the chamber 61. In the substrate processing
apparatus 60, high-frequency power supplies 64 and 65 are
respectively connected to the mounting stage 62 and the shower head
63, which also function as electrodes. Then, the mounting stage 62
and the shower head 63 supply high-frequency power to the inside of
the chamber 61, so that an electric field is generated in the
chamber 61. The electric field generates plasma from the processing
gas, so that the plasma performs plasma processing to the wafer
W.
Meanwhile, in order to perform the plasma processing uniformly to
the wafer W, it is necessary to make uniform the distribution of
plasma density on the wafer W. However, in order to make uniform
the distribution of plasma density, it is necessary to make uniform
the distribution of the electric field. Thus, for example, as in
the substrate processing apparatus 60, there has been developed a
substrate processing apparatus 60 in which branching waveguides
(power supply tubes) 66 connected to the high-frequency power
supply 65 and connected to the shower head 63 symmetrically around
the center of the shower head 63 are provided, to thereby make
uniform the distribution of the electric field (for example, see
Japanese Patent Laid-Open Publication No. 8-325759).
Further, the distribution of plasma density is influenced by the
distribution of processing gas introduced from the shower head.
Accordingly, it is known that as shown in FIG. 7, in an electrode
structure 70 of the substrate processing apparatus, two mutually
separated buffer chambers 72a and 72b are provided in a shower head
71, and a gas supply apparatus (not shown) for supplying processing
gas is connected to each of the buffer chambers 72a and 72b via
separate gas supply systems 73a and 73b, respectively, so as to
control the flow rate of the processing gas in each of the gas
supply systems 73a and 73b. In the electrode structure 70, each of
the buffer chambers 72a and 72b is communicated with the inside of
the chamber which houses a wafer, and the flow rate of the
processing gas supplied to the inside of the buffer chambers 72a
and 72b is controlled, so as to enable the shower head 71 to
control the distribution of the processing gas introduced into the
chamber.
Note that in the electrode structure 70, connecting sections 74a
and 74b, which respectively connect the gas supply systems 73a and
73b to the buffer chambers 72a and 72b, are arranged at the same
angle with respect to the center of the shower head 71, that is, in
the same radial direction.
However, when the etching processing is performed to the wafer W by
using the above described electrode structure 70 shown in FIG. 7,
micro abnormal discharge (arcing) has been sometimes generated on
the wafer W. Specifically, the arcing has been generated at the
positions symmetrical with the positions at which the connecting
sections 74a and 74b are arranged, with respect to the center of
the shower head 71. The arcing may destroy a wiring and an
insulating film of the semiconductor device which are formed on the
wafer W, and hence it is necessary to prevent the generation of the
arcing.
SUMMARY OF THE INVENTION
The present invention provides a substrate processing apparatus and
an electrode structure which are capable of preventing the abnormal
discharge from being generated on the substrate.
Accordingly, in a first aspect of the present invention, there is
provided a substrate processing apparatus comprising a housing
chamber configured to house a disc-like substrate, a mounting stage
arranged in the housing chamber and configured to enable the
substrate to be mounted thereon, a high-frequency power supply, a
gas supply apparatus configured to supply processing gas, and a
disc-like electrode structure connected to the high-frequency power
supply, and connected to the gas supply apparatus via at least one
gas supply system, wherein the electrode structure is arranged
opposite to the mounting stage, and has therein at least one buffer
chamber and a plurality of connecting sections connected to the gas
supply system, wherein the buffer chamber is communicated with the
inside of the housing chamber via a number of gas holes, and is
communicated with the gas supply system via the plurality of
connecting sections, and wherein the plurality of connecting
sections for the buffer chamber are arranged on the circumference
of a circle centering around the center of the electrode structure
at equal intervals.
According to the first aspect of the present invention, in the each
buffer chamber provided in the electrode structure connected to the
high-frequency power supply, the plurality of connecting sections
connected to the at least one gas supply system are arranged on the
circumference of a circle centering around the center of the
electrode structure at equal intervals. This enables the processing
gas to be uniformly supplied to the inside of the each buffer
chamber, so that the distribution of the processing gas introduced
into the housing chamber via the each buffer chamber can be made
uniform. Also, this enables the structure of the electrode
structure to be made symmetrical about the center of the electrode
structure, so that the distribution of the electric field generated
in the housing chamber can be made uniform. As a result, the
distribution of plasma density on the substrate can be made
uniform, so that the generation of the abnormal discharge on the
substrate can be prevented.
The first aspect of the present invention can provide a substrate
processing apparatus, wherein the electrode structure has therein a
plurality of buffer chambers, and wherein when the total number of
the connecting sections corresponding to all the buffer chambers is
set to n, the each connecting section is arranged at each
rotational angle of 360.degree./n.+-.3.degree. around the center of
the electrode structure.
According to the first aspect of the present invention, when the
total number of the connecting sections corresponding to all the
buffer chambers is set to n, the each connecting section is
arranged at each rotational angle of 360.degree./n.+-.3.degree.
about the center of the electrode structure. Thereby, the
distribution of the processing gas introduced into the housing
chamber via the each buffer chamber can be made more uniform, and
the structure of the electrode structure can be made more
symmetrical.
The first aspect of the present invention can provide a substrate
processing apparatus, wherein the electrode structure is configured
by a ceiling electrode plate, a cooling plate, and an upper
electrode body which are stacked in this order from the side of the
housing chamber, and the ceiling electrode plate, the cooling
plate, and the upper electrode body are made of a conductive
material, and wherein the plurality of connecting sections are
arranged on the upper electrode body, and the upper electrode body
is connected to the high-frequency power supply.
According to the first aspect of the present invention, the
plurality of connecting sections are arranged on the upper
electrode body connected to the high-frequency power supply, and
hence the structure of the upper electrode body to which the
high-frequency power is supplied can be made symmetrical. Thereby,
the distribution of the electric field generated in the housing
chamber can be surely made uniform.
The first aspect of the present invention can provide a substrate
processing apparatus, wherein at least a portion of the gas supply
system, which portion is connected to the connecting section, is
made of an insulating material.
According to the first aspect of the present invention, at least a
portion of the gas supply system, which portion is connected to the
connecting section, is made of an insulating material, and hence
the gas supply system does not affect the distribution of the
electric field. Thereby, the distribution of the electric field
generated in the housing chamber can be more surely made
uniform.
Accordingly, in a second aspect of the present invention, there is
provided an electrode structure provided in a substrate processing
apparatus which includes a housing chamber configured to house a
disc-like substrate, a mounting stage arranged in the housing
chamber and configured to enable the substrate to be mounted
thereon, a high-frequency power supply, and a gas supply apparatus
configured to supply processing gas, wherein the electrode
structure has a disc-like shape, and is connected to the
high-frequency power supply, and connected to the gas supply
apparatus via at least one gas supply system, wherein the electrode
structure is arranged opposite to the mounting stage, and has
therein at least one buffer chamber and a plurality of connecting
sections connected to the gas supply system, wherein the each
buffer chamber is communicated with the inside of the housing
chamber via a number of gas holes, and is communicated with the gas
supply system via the plurality of connecting sections, and wherein
the plurality of connecting sections for the each buffer chamber
are arranged on the circumference of a circle centering around the
center of the electrode structure at equal intervals.
The features and advantages of the invention will become more
apparent from the following detailed description taken in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view schematically showing a configuration of
a substrate processing apparatus according to an embodiment of the
present invention.
FIG. 2 is a plan view schematically showing a positional relation
between the shower head, the clamp, the central gas supply system,
and the peripheral gas supply system shown in FIG. 1.
FIG. 3 is a sectional view schematically showing a configuration of
a variation of the electrode structure according to the present
embodiment.
FIG. 4A and FIG. 4B are graphs showing the etching rate
distribution at the time when etching processing is performed to an
oxide film on a wafer by using the substrate processing apparatus
according to the present embodiment and a conventional substrate
processing apparatus: FIG. 4A shows the etching rate distribution
at the time when the conventional substrate processing apparatus is
used; and FIG. 4B shows the etching rate distribution at the time
when the substrate processing apparatus according to the present
embodiment is used.
FIG. 5A and FIG. 5B are graphs showing the etching rate
distribution at the time when etching processing is performed to a
photoresist film on the wafer by using the substrate processing
apparatus according to the present embodiment and the conventional
substrate processing apparatus: FIG. 5A shows the etching rate
distribution at the time when the conventional substrate processing
apparatus is used; and FIG. 5B shows the etching rate distribution
at the time when the substrate processing apparatus according to
the present embodiment is used.
FIG. 6 is a sectional view schematically showing a configuration of
the conventional substrate processing apparatus.
FIG. 7 is a plan view schematically showing a configuration of the
conventional electrode structure.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the following, embodiments according to the present invention
will be described with reference to the accompanying drawings.
First, a substrate processing apparatus according to an embodiment
of the present invention will be described.
FIG. 1 is a sectional view schematically showing a configuration of
a substrate processing apparatus according to an embodiment of the
present invention. The substrate processing apparatus is configured
such that etching processing as plasma processing is performed to a
semiconductor wafer as a substrate.
In FIG. 1, the substrate processing apparatus 10 has, for example,
a chamber 11 (housing chamber) which houses a disc-like
semiconductor wafer (hereinafter referred to as simply "wafer") W
having a diameter of 300 mm. A cylindrical susceptor supporting
stage 12 is arranged on the bottom surface inside the chamber 11,
and a cylindrical susceptor 13 (mounting stage) is arranged on the
susceptor supporting stage 12.
An ESC (Electrostatic Chuck) 14 (mounting stage) is arranged on the
susceptor 13. The ESC 14 is made of, for example, aluminum. A
ceramic material such as alumina, or the like, is thermally sprayed
onto the upper surface of the ESC 14 to form a thermally sprayed
film (not shown). In the thermally sprayed film, there is provided
an electrostatic electrode plate 16 to which a DC power supply 15
is electrically connected.
The wafer W housed in the chamber 11 is mounted on the upper
surface (hereinafter referred to as "mounting surface") of the ESC
14. When a positive DC voltage is applied to the electrostatic
electrode plate 16 from the DC power supply 15, a negative
potential is generated in the contact surface of the wafer W in
contact with the mounting surface, to cause a potential difference
between the electrostatic electrode plate 16 and the contact
surface of the wafer W. As a result, the wafer W is attracted to be
held on the mounting surface of the ESC 14 by the Coulomb force or
Johnson Rahbeck force resulting from the potential difference.
A plurality of heat transfer gas supply holes 17 are opened in the
mounting surface of the ESC14. The plurality of heat transfer gas
supply holes 17 are connected to a heat transfer gas supply section
(not shown) via a heat transfer gas supply line 18. The heat
transfer gas supply section supplies helium (He) gas as the heat
transfer gas between the contact surface of the wafer W and the
mounting surface via the heat transfer gas supply holes 17. The
helium gas supplied to the gap between the contact surface of the
wafer W and the mounting surface effectively transfers the heat of
the wafer W to the ESC 14.
The susceptor 13 is made of, for example, an aluminum alloy, and is
connected to a lower high-frequency power supply 19 via a lower
matching box (Matcher) 20, and the lower high-frequency power
supply 19 supplies high-frequency power of relatively low frequency
to the susceptor 13. Thereby, the susceptor 13 functions as a lower
electrode for supplying the high-frequency power to a processing
space S which is a space between the susceptor 13 and a shower head
24 as will be described below. Further, the lower matching box 20
matches the internal impedance of the lower high-frequency power
supply 19 with a load impedance.
Inside the susceptor supporting stage 12, for example, there is
provided an annular coolant chamber 21 extending in the
circumferential direction. To the coolant chamber 21,
low-temperature coolant such as, for example, cooling water and
Galden (registered trademark) fluid is circulated and supplied via
a coolant pipe 22 from a chiller unit (not shown). The susceptor
supporting stage 12 cooled by the low-temperature coolant cools the
wafer W via the ESC 14.
Further, an annular focus ring 23 is arranged on the ESC 14. The
focus ring 23 is made of a conductive material such as, for
example, silicon, and surrounds the wafer W which is attracted to
be held on the mounting surface of the ESC 14. Further, the focus
ring 23 converges plasma generated in the processing space S to the
surface of the wafer W, to thereby improve the efficiency of the
etching processing.
The disc-like shower head 24 (electrode structure) is arranged in
the ceiling section of the chamber 11, so as to face the wafer W
mounted on the ESC 14. The shower head 24 has a ceiling electrode
plate 25, a cooling plate 26, and an upper electrode supporting
body 27 (upper electrode body) which are stacked in this order from
the side of the processing space S. An upper high-frequency power
supply 30 is connected to the upper electrode supporting body 27
via a power supply tube 28 and an upper matching box 29. The upper
high-frequency power supply 30 supplies high-frequency power of a
relatively high frequency to the upper electrode supporting body
27. The ceiling electrode plate 25, the cooling plate 26, and the
upper electrode supporting body 27 are made of a conductive
material such as, for example, an aluminum alloy, and hence the
high-frequency power supplied to the upper electrode supporting
body 27 is supplied to the processing space S via the cooling plate
26 and the ceiling electrode plate 25. That is, the shower head 24
functions as an upper electrode for supplying the high-frequency
power to the processing space S. Note that the function of the
upper matching box 29 is the same as the function of the above
described lower matching box 20.
Note that the outer periphery of the shower head 24 is covered by
an annular dielectric member 31 which insulates the shower head 24
from the wall of the chamber 11. Further, the outside of the power
supply tube 28 is covered by a case-shaped grounding conductive
member 32, and the power supply tube 28 penetrates the
upper-surface central portion of the grounding conductive member
32. In the penetrating section, an insulating member 33 is provided
between the grounding conductive member 32 and the power supply
tube 28.
Further, in the shower head 24, the cooling plate 26 has, in the
inside thereof, a central buffer chamber 34 formed of a disc-like
space centering on the center (hereinafter referred to as "shower
head center") of the shower head 24, and a peripheral buffer
chamber 35 formed of an annular space concentric with the central
buffer chamber 34. The central buffer chamber 34 and the peripheral
buffer chamber 35 are separated by an annular partition wall member
such as, for example, an O ring 37. Further, the cooling plate 26
and the ceiling electrode plate 25 have a number of penetrating gas
holes 36 through which the central buffer chamber 34 and the
peripheral buffer chamber 35 are communicated with the processing
space S.
Further, in the shower head 24, a plurality of clamps 38 and 40
(connecting sections) made of a conductive material such as, for
example, aluminum are arranged on the upper electrode supporting
body 27. Specifically, two clamps 38 are arranged at positions
corresponding to the central buffer chamber 34, and two clamps 40
are arranged at positions corresponding to the peripheral buffer
chamber 35. The two clamps 38 are connected to a central gas supply
system 39 consisting of two branched pipes. The two clamps 40 are
connected to a peripheral gas supply system 41 consisting of two
branched pipes. Note that in the central gas supply system 39 and
the peripheral gas supply system 41, the portions respectively
connected to the clamps 38 and 40, specifically, the portions
existing in the inside of the grounding conductive member 32, are
made of an insulating material, specifically, a resin.
The central buffer chamber 34 is communicated with the central gas
supply system 39 via the two clamps 38, and the peripheral buffer
chamber 35 is communicated with the peripheral gas supply system 41
via the two clamps 40. Note that the central gas supply system 39
and the peripheral gas supply system 41 are connected to a branch
flow rate adjusting apparatus 42 which adjusts the flow rates of
the mixture of processing gas and additional gas to the central gas
supply system 39 and the peripheral gas supply system 41,
respectively. The branch flow rate adjusting apparatus 42 is
connected to a processing gas supply apparatus for supplying the
processing gas, and to an additional gas supply apparatus for
supplying the additional gas (both not shown). Note that the
processing gas in the present embodiment corresponds to, for
example, CF-based gas and oxygen gas, and the additional gas
corresponds to, for example, argon gas.
In the shower head 24, the mixed gas containing the processing gas
is introduced into the central buffer chamber 34 and the peripheral
buffer chamber 35 from the branch flow rate adjusting apparatus 42
via the central gas supply system 39 and the peripheral gas supply
system 41. The introduced mixed gas is introduced into the
processing space S via a number of the penetrating gas holes 36.
Therefore, the shower head 24 functions as a gas introducing
device. Further, in the shower head 24, a coolant chamber (not
shown) is provided in the cooling plate 26. A coolant such as, for
example, cooling water and Galden (registered trademark) fluid
introduced from coolant introducing sections 43a and 43b as will be
described below, is supplied to the inside of the coolant chamber.
The cooling plate 26 cools the mixed gas introduced into the
central buffer chamber 34 and the peripheral buffer chamber 35 by
the coolant in the coolant chamber.
In the present embodiment, the mixed gas introduced from the
penetrating gas holes 36 corresponding to the peripheral buffer
chamber 35 is distribution-diffused toward the periphery of the
wafer W mounted on the mounting surface, and the mixed gas
introduced from the penetrating gas holes 36 corresponding to the
central buffer chamber 34 is distribution-diffused toward the
central portion of the wafer W mounted on the mounting surface.
Note that the density distribution of the mixed gas on the wafer W
can be adjusted by adjusting the flow rate of the mixed gas which
is distributed to each of the central gas supply system 39 and the
peripheral gas supply system 41 by the branch flow rate adjusting
apparatus 42.
FIG. 2 is a plan view schematically showing a positional relation
between the shower head, the clamps, the central gas supply system,
and the peripheral gas supply system, which are shown in FIG.
1.
In FIG. 2, the two clamps 38 corresponding to the central buffer
chamber 34 are arranged on the circumference of a circle centering
around the shower head center at equal intervals, specifically, at
each 180.degree..+-.3.degree.. Further, the central buffer chamber
34 is formed of a disc-like space centering on the shower head
center. Therefore, in the central buffer chamber 34, the mixed gas
is introduced symmetrically around the shower head center. As a
result, the mixed gas can be uniformly supplied into the central
buffer chamber 34.
Further, the two clamps 40 corresponding to the peripheral buffer
chamber 35 are also arranged on the circumference of a circle
centering around the shower head center at equal intervals,
specifically, at each 180.degree..+-.3.degree.. The peripheral
buffer chamber 35 is formed of an annular space centering around
the shower head center. Therefore, also in the peripheral buffer
chamber 35, the mixed gas is introduced symmetrically around the
shower head center. As a result, the mixed gas can be uniformly
supplied to the inside of the peripheral buffer chamber 35.
Further, in the shower head 24, the total number of the clamps 38
and 40 is four, and each of the clamps 38 and 40 is arranged at
each rotational angle of 360.degree./4.+-.3.degree. in the
rotational system centering around the shower head center.
Specifically, the rotational angle between the adjacent clamps 38
and 40, which angle centers around the shower head center, is
90.degree..+-.3.degree.. Thereby, the mixed gas can be
symmetrically introduced into the processing space S via the
central buffer chamber 34 and the peripheral buffer chamber 35.
Therefore, the distribution of the mixed gas introduced into the
processing space S can be made more uniform.
Note that in the shower head 24, the coolant introducing sections
43a and 43b, and a PT sensor 44 which is a temperature measuring
sensor, are arranged so as to avoid the clamps 38 and 40, the
central gas supply system 39, and the peripheral gas supply system
41.
Returning to FIG. 1, in the substrate processing apparatus 10, a
high pass filter 45 is electrically connected to the susceptor 13,
and the high pass filter 45 passes the high-frequency power from
the upper high-frequency power supply 30 to the ground. Further, a
low pass filter 46 is electrically connected to the shower head 24,
and the low pass filter 46 passes the high-frequency power from the
lower high-frequency power supply 19 to the ground.
Further, in the substrate processing apparatus 10, a flow path,
through which the gas above the ESC 14 is discharged to the outside
of the chamber 11, is formed between the inside wall of the chamber
11 and the side surface of the ESC 14 (susceptor 13), and an
exhaust plate 47 is arranged in the middle of the flow path. The
exhaust plate 47 is a plate-shaped member having a number of holes,
and captures or reflects the plasma generated in the processing
space S, so as to prevent the leakage of the plasma.
In the substrate processing apparatus 10, when the mixed gas is
introduced into the processing space S from the shower head 24, and
when the high-frequency power is supplied to the processing space S
from the susceptor 13 and the shower head 24, a high frequency
electric field is generated in the processing space S, so that the
processing gas in the mixed gas is excited to become plasma. The
plasma performs etching processing to the wafer W.
Note that the operation of each component of the above described
substrate processing apparatus 10 is controlled by a CPU of a
controller (not shown) provided in the substrate processing
apparatus 10 on the basis of a program corresponding to the etching
processing.
According to the substrate processing apparatus 10 of the present
embodiment, the two clamps 38 corresponding to the central buffer
chamber 34 and connected to the central gas supply system 39 are
arranged on the circumference of a circle centering around the
shower head center at equal intervals. Further, the two clamps 40
corresponding to the peripheral buffer chamber 35 and connected to
the peripheral gas supply system 41 are arranged on the
circumference of a circle centering around the shower head center
at equal intervals. Thereby, the processing gas can be uniformly
supplied into the central buffer chamber 34 and the peripheral
buffer chamber 35, so that it is possible to make uniform the
distribution of the processing gas introduced into the processing
space S via the central buffer chamber 34 and the peripheral buffer
chamber 35. Further, the structure of the shower head 24 which
supplies high-frequency power to the processing space S can be made
symmetrical with respect to the shower head center, so that it is
possible to make uniform the distribution of the electric field
generated in the processing space S. As a result, the distribution
of the density of plasma generated on the wafer W can be made
uniform, so that it is possible to prevent the generation of arcing
on the wafer W.
In the above described substrate processing apparatus 10, the total
number of the clamps 38 and 40 is four, and hence the clamps 38 and
40 are arranged at each rotational angle of 90.degree..+-.3.degree.
around the shower head center. Therefore, the distribution of the
processing gas introduced into the processing space S can be made
more uniform. Further, the structure of the shower head 24 can be
made more symmetrical with respect to the shower head center.
Further, in the above described substrate processing apparatus 10,
the four clamps 38 and 40 are arranged on the upper electrode
supporting body 27 connected to the upper high-frequency power
supply 30, and hence the structure formed by the upper electrode
supporting body 27 to which the high-frequency power is supplied,
and formed by the four clamps 38 and 40 can be made symmetrical.
Thereby, the distribution of the electric field generated in the
processing space S can be surely made uniform.
Further, in the above described substrate processing apparatus 10,
the portions of the central gas supply system 39 and the peripheral
gas supply system 41, which portions are respectively connected to
the clamps 38 and 40, are made of a resin, and hence the
high-frequency power supplied to the upper electrode supporting
body 27 is prevented from being transmitted to the central gas
supply system 39 and the peripheral gas supply system 41 via the
clamps 38 and 40. Therefore, the central gas supply system 39 and
the peripheral gas supply system 41 do not affect the distribution
of the electric field in the processing space S, so that the
distribution of the electric field generated in the processing
space S can be more surely made uniform.
In the above described embodiment, two clamps are arranged on the
upper electrode supporting body 27 in correspondence with each of
the buffer chambers, but the number of the clamps arranged in
correspondence with each of the buffer chambers is not limited to
two. For example, the number of the clamps may be three or more. In
this case, N clamps corresponding to each of the buffer chambers
are arranged on the circumference of a circle centering around the
shower head center at equal intervals, specifically, at each
360.degree./N.
Further, the number of the buffer chambers provided in the shower
head 24 is not limited to two, but the number of the buffer
chambers may be one, or three or more. Even in this case, when the
total number of the clamps arranged on the upper electrode
supporting body 27 is set to n, the clamps are arranged at each
rotational angle of 360.degree./n.+-.3.degree. in the rotational
system centering around the shower head center. For example, as
shown in FIG. 3, when the shower head 24 has three buffer chambers,
and when the number of the clamps arranged on the upper electrode
supporting body 27 in correspondence with each of the buffer
chambers is two, the total number of the clamps is 6, and hence the
clamps are arranged at each rotational angle of
60.degree..+-.3.degree. in the rotational system centering around
the shower head center.
Further, in the above described embodiment, the coolant introducing
sections 43a and 43b are not symmetrically arranged with respect to
the shower head center. However, in the upper electrode supporting
body 27, the two coolant introducing sections may be symmetrically
arranged. Specifically, the two coolant introducing sections may be
arranged at equal intervals on the circumference of a circle
centering around the shower head center, for example, at each
180.degree..+-.3.degree.. Thereby, the structure of the shower head
24 can be made still more symmetrical about the shower head center,
so that the distribution of the electric field generated in the
processing space S can be surely made uniform. Further, the
plurality of components arranged on the upper electrode supporting
body 27 may be preferably arranged as symmetrically as possible
with respect to the shower head center.
Note that in the above described embodiment, the location tolerance
in the arrangement of the clamps and the like is set to
.+-.3.degree.. However, the general machining tolerance is also in
general .+-.3.degree., and hence special tolerance management to
realize the above described arrangement of the clamps and the like
is not needed. Thereby, it is possible to prevent the increase in
manufacturing cost of the shower head 24.
EXAMPLE
Next, an example according to the present invention will be
specifically described.
Example
First, when it was observed whether or not arcing was generated on
a wafer W during the etching processing performed to the wafer W in
the substrate processing apparatus 10, the generation of the arcing
was not observed. Further, when the charge distribution on the
surface of the wafer W was investigated, it was confirmed that the
charges were distributed in the state of concentric circles, and
that uneven distribution of the charges in the circumferential
direction was not generated.
Further, the etching processing was performed to the oxide film on
the wafer W in the substrate processing apparatus 10, and the
distribution of etching rate at this time was observed. The
observation result is shown in the graph of FIG. 4B. Further, the
etching processing was performed to the photoresist film on the
wafer W in the substrate processing apparatus 10, and the
distribution of etching rate at this time was observed. The
observation result is shown in the graph of FIG. 5B.
Comparison Example
First, when it was observed whether or not arcing was generated on
a wafer W during the etching processing performed to the wafer W in
the substrate processing apparatus (hereinafter referred to as
"conventional substrate processing apparatus") provided with the
electrode structure 70 shown in FIG. 7, it was confirmed that the
arcing was generated at positions symmetrical with the positions at
which the connecting sections 74a and 74b are arranged, with
respect to the center of the shower head 71. Further, when the
charge distribution on the surface of the wafer W was investigated,
it was confirmed that uneven distribution of the charges was
generated at positions symmetrical with the positions at which the
connecting sections 74a and 74b are arranged, with respect to the
center of the shower head 71.
Further, the etching processing was performed to the oxide film on
the wafer W in the conventional substrate processing apparatus, the
distribution of etching rate at this time was observed. The
observation result is shown in the graph of FIG. 4A. Further, the
etching processing was performed to the photoresist film on the
wafer W in the conventional substrate processing apparatus, the
distribution of etching rate at this time was observed. The
observation result is shown in the graph of FIG. 5A.
By comparing Example with Comparison Example, it was seen that in
Comparison Example, the arcing was generated, and the uneven
distribution of the charges was also generated, while in Example,
the arcing was not generated, and also the uneven distribution of
the charges was not generated. From this fact, it was seen that in
Example, the distribution of the processing gas introduced into the
processing space S was made uniform, and the distribution of the
electric field generated in the processing space S was also made
uniform, as a result of which the distribution of the density of
plasma generated on the wafer W was made uniform.
In addition, the graph of FIG. 4A was compared with the graph of
FIG. 4B, and further the graph of FIG. 5A was compared with the
graph of FIG. 5B. As a result, it was seen that in any of the
etching processing of the oxide film and the etching processing of
the photoresist film, the dispersion in the distribution of etching
rate in Example is smaller than the dispersion in the distribution
of etching rate in Comparison Example. Also from this fact, it was
seen that in Example, the distribution of the density of plasma
generated on the wafer W was made uniform.
* * * * *